#include <iostream>
#include <math.h>

using namespace std;

struct xy
{
    double x, y;
};

double dis(xy *a, xy *b);

int main()
{
    xy *zuobiao = new xy[3];
    for (int i = 0; i < 3; i++)
    {
        cin >> zuobiao[i].x >> zuobiao[i].y;
    }
    double sum = 0;
    for (int i = 0; i < 2; i++)
    {
        for (int j = i + 1; j < 3; j++)
        {
            sum += dis(zuobiao + i, zuobiao + j);
        }
    }
    printf("%.2f", sum);
    return 0;
}

double dis(xy *a, xy *b)
{
    double len = sqrt(pow((a->x - b->x), 2) + pow((a->y - b->y), 2));
    return len;
}